|What's the difference between a four-stroke engine and a two-stroke engine? This topic seems to come up every once in a while, so I'll record the answer for posterity:
Four-stroke engines are in pretty much all cars and trucks driving on the road, whether gas or diesel or sporty or work-y or anything else. The "four-stroke" refers to the four parts of a cycle: Intake, compression, combustion, exhaust. HowStuffWorks has a great article with an animation.
Two-stroke engines are generally in lawn mowers, leaf blowers, chain saws, and dirt bikes. The "two-stroke" refers to the two parts of a cycle: Compression and combustion. Again, HowStuffWorks has a great article with an animation.
Why use either one? Two-stroke engines produce more power and weigh less, but they're also louder, require a mixture of oil and gas, don't last as long, aren't as fuel-efficient, and produce more pollution than four-stroke engines. The reason they're used is because of their power and weight properties. #science